Macro Area Camera for an Infrared (IR) Microscope

Abstract

A novel arrangement of Schwarzschild Cassegrainian objective coupled with a far-field visible imaging system that does not interfere with the interrogating (IR) beam is introduced. Typical (IR) microscopes that incorporate a Cassegrainian objective have difficulty in locating desired target sample regions based on the inherent limited field-of-view. Because commonly applied visible imaging accessories upstream must use the same numerical aperture based on the reflective geometry, such systems also suffer a limited field of view. To overcome such difficulties, the novel embodiments herein involve placing a visible camera with its optical axis collinear with the IR and primary visible beampath of the microscope but outside the optical path that provides the (IR) image magnification.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to the field of optical microscopy. More particularly, the present invention relates to a novel reflective infrared microscope objective that enables simultaneous viewing of both, the area of interest and a significantly wider field of view.[0003]2. Discussion of the Related Art[0004]Infrared (IR) and in particular Fourier Transform infrared (FTIR) microscope systems enable optical spectroscopic interrogation of substantially small samples (e.g., areas of about 25 μm×25 μm) by mapping the acquired image data of a larger area of a sample with a defined spatial resolution. Accordingly, a beneficial aspect of the FTIR microscope is the ability to collect infrared spectra from a much smaller, defined area of the sample matrix. FTIR microscopy in particular can provide spectral information of a very small contaminant embedded in a sample or particular details regarding chemical constituents or o...

AI Technical Summary

Benefits of technology

[0009]The present invention is directed to an Infrared (IR) microscope that is configured with a visible camera having its optical axis collinear with the (IR) and primary visible beampath of the microscope but outside the optical path that provides the image magnification. In particular, the Infrared (IR) microscope disclosed herein includes a reflective objective configured with a primary and a secondary mirror, wherein the primary and the secondary mirror causes incoming (IR) radiation to focus at a sample plane after passing through the reflective objective to form sample induced magnified imaging and spectroscopic information and an arrayed camera as coupled to the secondary mirror provides a wide field-of-view to enable ease of targeting regions of the sample when operating the (IR) system. It is to also be appreciated that the camera's optical axis is further configured to be collinear with the optical axis of the incoming (IR) radiation but outside the optical path so as to not interfere with the incoming (IR) radiation that provides magnified imaging and spectroscopic information.

[0010]Accordingly, the present provides for the integration of a large field of view camera and illumination means (e.g., LED multi-angle illuminators) that enables: 1) the video capturing of a significantly larger area than the one provided by the objective, 2) significantly reduces the video collection time (typically one frame instead of hundreds), which also improves the overall analysis time (cost) 3) provides brighter illumination than built in Abbe or Koehler type illuminators, which helps to cover a wider range of samples with different optical and surface properties and 4) opens the simplicity of finding specimens through large field of view observation to microscopes equipped with manual stage and single / fixed objective, hence significantly reducing the implied cost.

Problems solved by technology

However, using reflective optics limits the flexibility the designer has when developing a microscope with an appropriate magnification but with a desired visible wide field-of-view for targeting desired samples and often makes variable magnification impractical.

This particular arrangement, however, has provided for a long-standing problem in the field of IR microscopy because, as known to one of ordinary skill in the art, although the visible field-of-view tends to be somewhat larger than the infrared field-of-view despite traveling through the same microscope beampath, the visible arrangement is still quite restricted by the numerical aperture (NA) and magnification of the objective.

However, this procedure also shows some inconveniences, such as: 1) the quality of the stitched, reconstructed image is subject to stage calibration and alignment accuracy to image vignetting and other illumination artifacts 2) the time required to acquire a large image composed by hundreds of frames significantly compromises the overall measurement cost per analysis 3) the illumination through the microscope objective is subject to intrinsic power of the visible light illuminators, sample reflectivity or opaqueness, etc., and 4) without the aid of a well calibrated motorized stage (i.e.; a manual stage) a large field of view image acquisition—without changing the objective magnification—is impossible.

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